At the High Court in Glasgow dad-of-three Richard Green, 63, pleaded guilty to the culpable homicide of John Paul Green, 32, on January 7, last year, at Everard Drive, Glasgow.
Green, who was on trial for murder, had the reduced plea accepted.
The court had earlier heard the victim, who had alcohol and drug problems, had turned up drunk at his dad's house and demanded to know why his father had not protected him from alleged childhood sexual abuse.
Green told his son he'd been unaware of any abuse. During an altercation, Green stabbed his son.
Sentence was deferred.